Conventionally, the sheet materials such as paper, plastic, fabric, metal foil, etc. are cut into a defined dimension with a cutting apparatus such as a sheet cutter and a Guillotine cutter and, if required, defectives are removed by a defect-detecting apparatus or through a visual inspection by an inspector, and a defined number of sheets is divided as one unit (referred to as a "stacklet" hereinafter) and packaged and shipped.
Therefore, an automatic paper inserting apparatus has been widely used to insert paper tape strips (only referred to as "tape" hereinafter) at every defined number of cut sheets sent to the platform continuously and piled on the platform. However, the conventional apparatus utilizes a procedure of cutting the tape supplied continuously at every insertion. Consequently, an insertion to an erronous number of sheets and also a complete penetration of the tape between the cut sheets can occur due to the irregularity of the piling of the cut sheets and due to mutual adhesion of the piled cut sheets.
In some cases, the tape pushed for insertion slips away in failure to be inserted or the length of insertion is too short to be held between the sheets with no slippage from the side of the stack.
Therefore, the worker (or the supervisor) takes care for the discovery of these errors during the packaging of the cut sheets and the selection of defectives. However, they are sometimes overlooked and it becomes especially a big problem when the inserted tape penetrates between the cut sheets.
Thus, in the case where the stacklet is fed to the printer with the tape being penetrated between the cut sheets, the penetrated tape undesirably adheres to the printing plate to injure it.
Hence, the applicant of the present invention had filed an invention of "a paper inserting apparatus" as Japanese Utility Model Application No. 198,750 of 1987. The application is directed to an apparatus in which an elongated flexible leaf element (hereinafter referred simply as "elongated leaf") supported by a reciprocal drive mechanism so as to be guided to the position of insertion through a guide path together with the tape is provided and the end of the elongated leaf is pressed on one side of the continuous tape at the position of insertion to form a fold on the tape and thus to insert the tape in a trap configuration. Such a constitution has an excellent characteristic for solving the above-mentioned difficulties.
However, in the continuous use for a long period of the paper inserting apparatus of the above-memtioned constitution, several difficulties can occur at times in the guide path 101a of the guide bar 101 shown in the attached FIGS. 15 to 17 (corresponding to FIGS. 1 to 3 of the above application) such that the elongated leaf 102 may be bent by the compression due to the pushing force applied to its back end and also on the friction between it and the path surface, or that the trapped insertion portion of the continuous tape 104 inserted at every stacklet of the defined number of sheets in the end wall surface 103b of the stack 103 of the cut paper sheets 103a.
As mentioned above, in the case where the difficulty of bending the elongated blade occurs, it is countermeasured by stopping the operation of the apparatus, removing the inserting apparatus causing the error and replacing it by a new one. However, no product can be manufactured during the stoppage of the apparatus to decrease largely the yield of the product.
In the case of the difficulty that the tape is slipping from the side wall of the stack, the worker should transfer the stack on the platform once to another place and check if the number of the cut sheets at the site where the insertion is slipped out is as defined to give a heavy charge on the worker.
By an investigation of the cause of these difficulties, the followings was found as the causes. As shown in FIG. 17, a pusher 106 driven by the first air cylinder 105 is used to push the elongated leaf 102 and the tape 104. When this pusher is moved forward, an engaging lever 107 pivottably mounted on the pusher 106 is rotated counterclockwise by the pushing nut 108 equipped to the end of the rod 105a and thus the end edge 107c of the engaging lever presses the tape to the wall of the guide path 101a and slides it and moves together with the pusher 106 pushed by the support shaft 105a to push forward the tape together with the pushing of the folded front end by the elongated leaf 102. Accordingly, the engaging force of the end edge of the lever 107 on the tape can be hardly constant in accordance with the pressing and sliding condition between the tape 104 and the wall surface to cause irregular sliding of the end edge 107c of the lever on the tape surface and thus to shorten the sending length of the tape. Also when the pusher returns, the engaging force of the end edge of the lever is not completely released and thus the tape is pushed back to some extent resulting in shortening the sending length of the tape. Accordingly, it was found that the depth of the insertion is decreased to ease the slipping out of the inserted tape.
Furthermore, when the tape is pushed forward by the unstable engaging force of the end edge of the lever and the pushing force of the elongaged leaf 102 at the front end, the cross section of the guide path 101a provided in the guide plate 101 should be sufficiently large to decrease the resistance agianst the movement. Accordingly, the shape of its cross section is such that a rectangle is combined on an upset isosceles trapezoid. In this structure, the top of the upset isosceles trapezoid is open and the space of it is far larger than the total of the thickness of the elongated leaf and that of the tape and the isosceles portion is narrowed gradually to the lower opening.
Accordingly, when the elongated leaf is driven to forward together with the tape by pushing forward the pusher for the tape insertion, the folded portion of the tape going to be inserted to the front end wall of the stack is bended for several steps in the sending direction in the guide path by the resistance caused by the upper portion of the stack. Further, the elongated leaf is pressed on the isosceles portion from inside and is deformed so that it is also bent outward and protruded from the opening when the leaf is bent in the sending direction. It was found that these bending and deformation occured at every insertion process resulting in breaking the elongated leaf by fatigue.